Immunocompetent cells in the normal dental pulp

The existence and location of various immunocompetent cells in the human dental pulp were investigated. Pulp tissue for analysis was obtained both from clinically intact pre-molars and from third molars without restorations or caries. Frozen and acetone-fixed pulp tissue sections were subjected to indirect immunohistochemistry with monoclonal antibodies to the following cell types: all peripheral T cells, helper/inducer T cells, cytotoxic/suppressor T cells, macrophages, B cells, and Class II antigen-expressing cells. Dendritic cells expressing Class II antigens (HLA-DR, -DQ), indicating a capacity for presentation of antigen to T helper cells, were seen in the odontoblastic layer as well as in the central portions of the pulp tissue. T lymphocytes, divided into helper/inducer and cytotoxic/suppressor cells, were observed in all pulp specimens. B cells were not seen in any of the pulp samples examined. The data demonstrate that the human dental pulp is equipped with immunocompetent cells essential for the initiation of immunological responses.